linux-kernel - Re: [PATCH] kernel/compat.c: mark expected switch fall-throughs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAK8P3a31Cp_COwjuOm6uG_23M3Ys4tJTB33jBENj-so0jkhgzg@mail.gmail.com>
Date:   Tue, 16 Apr 2019 10:32:55 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Kees Cook <keescook@...omium.org>, Jann Horn <jannh@...gle.com>
Subject: Re: [PATCH] kernel/compat.c: mark expected switch fall-throughs

On Tue, Apr 16, 2019 at 9:29 AM Stephen Rothwell <sfr@...b.auug.org.au> wrote:
>
> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
> where we are expecting to fall through.
>
> This patch aims to suppress up to 3 missing-break-in-switch false
> positives on some architectures.
>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Deepa Dinamani <deepa.kernel@...il.com>
> Cc: Gustavo A. R. Silva <gustavo@...eddedor.com>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Jann Horn <jannh@...gle.com>
> Signed-off-by: Stephen Rothwell <sfr@...b.auug.org.au>

Acked-by: Arnd Bergmann <arnd@...db.de>

> ---
>  kernel/compat.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> I know that this makes the lines longer than 80 characters, but I
> though that this was better than adding new lines.

It's a bit inconsistent though since put_compat_sigset() has the
comments in separate lines, as of commit 89976005536c
("include/linux/compat.h: mark expected switch fall-throughs").

I don't care either way, but it might be better to do it the same way
for both.

We could also consider just getting rid of put_compat_sigset() and
get_compat_sigset() but replacing them with a combined
put_sigset()/get_sigset() that does the right thing for both native
and compat tasks. This lets us kill a couple of compat system
calls that only differ in their sigset_t argument. On little-endian
systems (which are the vast majority of the installed base), there
is no difference anyway there is no overhead anyway since
native and compat sigset_t are identical.

        Arnd